Abstract
Purpose
To characterize risk factors for patients who underwent multiple-revision hip arthroscopies and report survivorship at a minimum 2 years after hip arthroscopy.
Methods
Patients aged 18-65 years who underwent revision hip arthroscopy between January 2011 and September 2018 with ≥2-year follow-up were included. Exclusion criteria were age <18 or >65 years at time of surgery, center-edge angle <20°, previous ipsilateral periacetabular osteotomy, or refusal to participate. Procedures were categorized as first (R1), second (R2), or third or more (R3+) revisions. Demographics, preoperative radiographic measurements, baseline patient-reported outcomes (PROs), intraoperative findings, and survivorship were compared across groups and between those requiring further surgery or total hip arthroplasty (THA) and those who did not. Survivorship was defined as re-revision and arthroplasty-free survival. PROs included modified Harris Hip Score, Hip Outcome Score – Activities Daily Living, HOS-Sport, Western Ontario and McMaster Universities Osteoarthritis Index, and Short Form Physical and Mental Component Scores (12-Item Short Form Physical Component Score/Mental Component Score).
Results
A total of 284 hips (246 patients) met inclusion criteria, with mean follow-up of 4.3 ± 2.1 years. Female sex (52% vs 63% vs 78%, P = .03), primary hip arthroscopy at an outside institution (62% vs 78% vs 96%, P < .001), smaller alpha angle (64° vs 56° vs 50°, P < .001), and worse baseline PROs (modified Harris Hip Score, Hip Outcome Score – Activities Daily Living, HOS-Sport, Western Ontario and McMaster Universities Osteoarthritis Index; P = .05, P = .01, P < .001, P = .01) were associated with more previous revisions. Failure incidence did not differ between groups (P = .29), but the hazard ratio for further surgery or THA was greater for R3+ versus R1 (hazard ratio 2.4, 95% confidence interval 1.04-5.38, P = .04).
Conclusions
At a minimum 2-year follow-up, more prior revisions were associated with female sex, lower baseline PROs, capsular deficiency, and greater failure risk. Patients with lower nondysplastic lateral center-edge angles, severe acetabular cartilage damage, or ≥3 revisions had elevated risk for re-revision or THA.
Level of Evidence
Level IV, therapeutic case series.
It has been well-established that patient-reported outcomes (PROs) improve after revision hip arthroscopy (RHA); however, they remain inferior to those after a successful primary hip arthroscopy.1, 2, 3, 4, 5, 6 Risk factors associated with the need for revision surgery most commonly include age, sex, adhesion formation, low case volume on the part of the surgeon, failure to identify borderline dysplasia, atypical impingement, capsular incompetency, residual osseous impingement (cam or pincer), over-resection of the cam deformity, labral retear or deficiency, ligamentum teres dysfunction, loose bodies, and chondral lesions.1, 2, 3,7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19
RHA is necessary in up to 9% of primary cases11; however, multiple-revision hip arthroscopy (MRHA) is not uncommon, having been reported to occur in up to 14% of patients after their first revision procedure.2,9 It has been shown in both the adult and adolescent populations that each additional revision procedure results in poorer outcomes scores.5,6 Yet, there is a paucity of evidence focused on the risk factors or survivorship after MRHA.
The purpose of this study was to characterize risk factors for patients who underwent MRHAs and report survivorship at a minimum 2 years after hip arthroscopy. It was hypothesized that risk factors for MRHA would be identified and that survivorship would be lower than the reported rates for solitary revision hip arthroscopies.
Methods
Patient Selection
This retrospective study was approved by the Vail Health institutional review board (#2020-045). Patients who underwent revision hip arthroscopy by a single surgeon (M.J.P.) between January 2011 and September 2018 with available minimum 2-year follow-up were included. Exclusion criteria were age younger than 18 or older than 65 years of age at time of surgery, center-edge angle <20°, previous ipsilateral periacetabular osteotomy, or refusal to participate. Demographic, previous surgical history, preoperative radiographic measurements, and intraoperative findings and procedures data were collected from the medical record. Baseline PROs collected before the index revision surgery were evaluated, including modified Harris Hip Score, Hip Outcome Score (HOS) Activities of Daily Living and Sport, Western Ontario and McMaster Universities Osteoarthritis Index, and 12-Item Short Form Physical Component Score and Mental Component Score. Patients were contacted at a minimum of 2 years after surgery to determine whether they had undergone additional procedures, including subsequent hip arthroscopy or conversion to total hip arthroplasty (THA). Survivorship was defined as not requiring a subsequent revision surgery or conversion to THA.
Clinical Evaluation
Preoperative evaluation of patients consisted of detailed clinical history, physical examination of the hip, and imaging studies. Tests for femoroacetabular impingement (FAI), such as the anterior impingement test and the flexion abduction external rotation distance test, were performed. For the purpose of evaluating hip instability, the physical examination included the abduction-hyperextension-external rotation test. The hip dial test was performed to determine the status of the capsule. Imaging tests included anteroposterior pelvic, false profile, and 45° Dunn radiographs and 3-Tesla magnetic resonance imaging without contrast.
Indications for RHA included patients with hip pain and instability who are not responsive to nonoperative treatment with evidence of intra- or extra-articular hip pathology, including labral tear or deficiency, residual FAI, cam over-resection, adhesion formation, capsular deficiency, chondral lesions and/or ligamentum teres pathology. Patient selection included radiographic joint space greater than 2 mm, no evidence of dysplasia as determined by radiographs (lateral center-edge angle [LCEA] ≥20°), desire to avoid THA, and shared decision making after thorough discussion of risks and benefits of revision hip arthroscopy. All included revision and re-revision surgeries were performed by the senior author (M.J.P.).
Surgical Technique
Patients underwent epidural anesthesia and were placed in modified supine position (10° of flexion, 15° of internal rotation, 10° of lateral tilt, and neutral abduction) with placement of anterolateral and midanterior arthroscopic portals. Diagnostic hip arthroscopy was performed to assess for structural lesions and carefully release adhesions. A hip dynamic examination was performed to evaluate the labral seal mechanism. The labral tissue was then assessed to determine labral height, quality, and presence of chondrolabral junction integrity. The decision to proceed with labral augmentation or reconstruction was made intraoperatively when complete focal or global loss of labral tissue or calcified labrum was present.20,21 Capsular spacer was performed when there was sufficient labral tissue but capuslolabral adhesions present.22 The femoral head and acetabular chondral surfaces were evaluated and cartilage pathology was graded using the Outerbridge grading system. Chondroplasty was performed to remove unstable cartilage. Microfracture was performed for focal and contained full-thickness articular cartilage lesions (grade III/IV) on the acetabulum and/or femoral head.23 If pincer-type FAI was identified, acetabular rim trimming was performed, and if cam-type FAI was identified, a femoral head-neck osteoplasty was performed. The extent of impingement correction was based on a dynamic bony impingement examination. Ligamentum teres pathology, such as fraying, partial tearing, hypertrophy, or synovitis, was debrided when indicated. The quality and quantity of capsular tissue remaining was evaluated. The decision to proceed with capsular reconstruction was made intraoperatively when the remaining tissue was not adequate for repair.24
Postoperative Rehabilitation
Patients followed a similar protocol with individualization according to each patient’s needs and intraoperative procedures performed. For the prevention of adhesions, passive exercises such as continuous passive motion (CPM) and early stationary bicycling were started immediately postoperatively. The CPM machine is used daily for 4 weeks. A hip brace is worn for approximately 3 weeks to prevent excessive hyperextension and abduction. Patients are limited to 20 pounds of flat-foot weightbearing for 2 to 3 weeks after surgery or 6 to 8 weeks if microfracture was performed. Return to full function and sports was permitted when the patient completed all stages of the rehabilitation protocol and was able to pass the Hip Sports Test.25
Statistical Analysis
For analysis, revision hip arthroscopy procedures were grouped on the basis of undergoing a first revision (R1), second revision (R2), or third or more revision surgery (R3+). Bivariate comparisons were made between hips requiring subsequent revision or conversion to THA and those who did not. A single-covariate survival model was constructed to assess the unadjusted association between revision group and risk for subsequent revision surgery or conversion to THA. In addition, a multivariable Cox proportional hazards model was used to adjust for age, sex, and the presence of severe chondral defects (Outerbridge grade 3/4). Results were considered significant at P < .05 or if the 95% confidence interval (CI) for odds ratios did not contain 1.0 (alpha = 0.05). All statistical analyses were performed using the statistical computing language R, version 4.1.2 (R Core Team, Vienna, Austria, with additional packages gtsummary, survival, and survminer).26,27
Results
A total of 284 hips from 216 unique patients met inclusion criteria, and the mean follow-up was 4.3 ± 2.1 years. The R1 group included 194 hips, the R2 group included 67 hips, and the R3+ group included 23 hips. Table 1 shows demographic, previous surgical history, preoperative radiographic measurements, intraoperative findings, and procedures performed according to each revision group. Female sex (52% vs 63% vs 78%, P = .03), primary hip arthroscopy performed at an outside institution (62% vs 78% vs 96%, P < .001), smaller alpha angle (64° vs 56° vs 50°, P < .001), and worse baseline PRO scores (modified Harris Hip Score, HOS-Activities of Daily Living, HOS-Sport, Western Ontario and McMaster Universities Osteoarthritis Index, P = .05, P = .01, P < .001, P = .01, respectively) were associated with more previous revision surgeries (R1 vs R2 vs R3+, P value). The most common pathologies treated during MRHA include adhesions, residual impingement, labral pathology, and capsular deficiency. The R3+ group had lower prevalence of labral tears (47% vs 31% vs 17%, P = .005), greater prevalence of severe chondral defects (Outerbridge grade 3/4) (26% vs 15% vs 30%, P = .14), and greater likelihood of treatment with labral debridement (21% vs 30% vs 52%, P = .004) and capsular reconstruction (13% vs 28% vs 43%, P < .001) during the index revision surgery (R1 vs R2 vs R3+, P value).
Table 1.
Patient Demographics and Preoperative Assessment, Intraoperative Findings and Treatments, and Survivorship on the Basis of Revision Groups∗
| Demographic and Preoperative Data | Overall, N = 284 | R1 n = 194 | R2 n = 67 | R3+ n = 23 | P Value |
|---|---|---|---|---|---|
| Age, yr | 34 ± 11 | 34 ± 11 | 33 ± 10 | 33 ± 10 | .71 |
| Sex | |||||
| Male | 123 (43) | 93 (48) | 25 (37) | 5 (23) | .03 |
| Female | 161 (57) | 101 (52) | 42 (63) | 18 (78) | |
| Tönnis grade | .09 | ||||
| 0 | 106 (38) | 74 (40) | 27 (41) | 5 (22) | |
| 1 | 141 (51) | 92 (49) | 31 (47) | 18 (78) | |
| 2 | 29 (11) | 21 (11) | 8 (12) | 0 | |
| Minimum joint space, mm | 3.25 ± 0.73 | 3.26 ± 0.69 | 3.27 ± 0.81 | 3.01 ± 0.79 | .24 |
| Alpha angle, ° | 61 ± 17 | 64 ± 16 | 56 ± 17 | 50 ± 16 | <.001 |
| Lateral center-edge angle, ° | 31 ± 7 | 31 ± 7 | 31 ± 6 | 30 ± 6 | .49 |
| Sharp’s angle, ° | 39 ± 6 | 39 ± 5 | 38 ± 5 | 38 ± 7 | .19 |
| Years from previous surgery to revision | 2.9 ± 2.5 | 3.1 ± 2.7 | 2.6 ± 2.2 | 2.8 ± 2.5 | .52 |
| Primary hip arthroscopy performed by senior author | 90 (32) | 74 (38) | 15 (22) | 1 (4.3) | <.001 |
| Primary labral treatment | |||||
| No treatment | 18 (6) | 8 (4) | 6 (9) | 4 (17) | .83 |
| Debridement | 85 (30) | 56 (29) | 22 (33) | 7 (30) | .67 |
| Repair | 178 (63) | 127 (65) | 39 (58) | 12 (52) | .32 |
| Reconstruction | 3 (1) | 3 (2) | 0 | 0 | .67 |
| Baseline outcome scores | |||||
| mHHS | 59 ± 16 | 61 ± 15 | 56 ± 17 | 57 ± 16 | .05 |
| HOS-ADL | 64 ± 17 | 66 ± 17 | 59 ± 18 | 60 ± 15 | .01 |
| HOS-Sport | 39 ± 24 | 43 ± 24 | 33 ± 24 | 27 ± 19 | <.001 |
| WOMAC | 31 ± 16 | 29 ± 15 | 36 ± 16 | 35 ± 12 | .01 |
| SF-12 PCS | 39 ± 9 | 40 ± 9 | 37 ± 9 | 35 ± 7 | .005 |
| SF-12 MCS | 51 ± 11 | 51 ± 11 | 50 ± 10 | 50 ± 12 | .005 |
NOTE. R1 = undergoing first revision; R2 = undergoing second revision; R3+ = undergoing third or more revision.
HOS-ADL, Hip Outcome Score Activities of Daily Living; HOL-Sport, Hip Outcome Score Sport Score; mHHS, modified Harris Hip Score; SF-12 MCS, 12-Item Short Form Mental Component Score; SF-12 PCS, 12-Item Short Form Physical Component Score; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.
Data are represented as mean ± standard deviation or number of patients (% of total).
The Kaplan-Meier curve based on the revision groups with failure defined as requiring re-revision surgery or conversion to THA is shown in Figure 1. Comparison of hips requiring re-revision or THA and those not requiring reoperation from the R1, R2, and R3+ revision groups is displayed in Table 2, Table 3, Table 4. Hips requiring subsequent revision or THA (n = 55, 19%) had significantly lower LCEA (29 ± 8 vs 31 ± 6, P = .01) and greater prevalence of severe acetabular cartilage defects (33% vs 19%, P = .03) compared with hips not requiring subsequent surgery (n = 229, 81%), respectively. There was a nonsignificant greater prevalence of Tönnis grade 2 (19% vs 9%, P = .08) and decreased minimal joint space (3.07 vs 3.29, P = .06) among hips who had subsequent surgery compared with those who did not.
Fig 1.
Kaplan-Meier curve determined on the basis of revision groups. (THA, total hip arthroplasty.)
Table 2.
Intraoperative Findings and Treatments, and Survivorship on the Basis of Revision Groups∗
| Overall, N = 284 | R1 n = 194 | R2 n = 67 | R3+ n = 23 | P Value | |
|---|---|---|---|---|---|
| Intraoperative findings | |||||
| Labrum | |||||
| Tear | 116 (41) | 91 (47) | 21 (31) | 4 (17) | .005 |
| Deficient | 39 (14) | 22 (11) | 12 (18) | 5 (22) | .17 |
| Chondral lesions (Outerbridge grade 3/4) | |||||
| Femoral head | 67 (24) | 50 (26) | 10 (15) | 7 (30) | .14 |
| Acetabulum | 62 (22) | 50 (26) | 8 (12) | 4 (17) | .05 |
| Residual femoroacetabular impingement | |||||
| Cam | 184 (76) | 133 (70) | 39 (58) | 12 (52) | .25 |
| Pincer | 167 (60) | 115 (61) | 39 (58) | 13 (57) | .99 |
| Adhesions | 259 (92) | 176 (92) | 61 (92) | 22 (96) | .88 |
| Ligamentum teres | |||||
| Hypertrophy | 56 (20) | 42 (22) | 10 (15) | 4 (17) | .49 |
| Synovitis | 214 (75) | 150 (77) | 44 (66) | 20 (87) | .06 |
| Tear | 171 (60) | 123 (63) | 33 (49) | 15 (65) | .11 |
| Procedures performed during revision surgery | |||||
| Labral treatment | |||||
| Debridement | 73 (26) | 41 (21) | 20 (30) | 12 (52) | .004 |
| Repair | 90 (32) | 69 (36) | 15 (22) | 6 (26) | .11 |
| Augmentation | 27 (10) | 20 (10) | 4 (6) | 3 (13) | .48 |
| Reconstruction | 112 (39) | 72 (37) | 32 (48) | 8 (35) | .27 |
| Microfracture | |||||
| Femoral head | 28 (10) | 21 (11) | 4 (6) | 3 (13) | .44 |
| Acetabulum | 26 (9) | 22 (11) | 3 (5) | 1 (4) | .20 |
| Capsular spacer | 59 (21) | 44 (23) | 9 (13) | 6 (26) | .20 |
| Capsular reconstruction | 55 (19) | 26 (13) | 19 (28) | 10 (43) | <.001 |
| Lysis of adhesions | 259 (92) | 176 (92) | 61 (92) | 22 (96) | .88 |
| Ligamentum teres treatment | |||||
| Debridement | 204 (72) | 143 (74) | 43 (64) | 18 (78) | .25 |
| Primary repair | 3 (1) | 3 (2) | 0 | 0 | .67 |
| Reconstruction | 3 (1) | 2 (1) | 1 (2) | 0 | .99 |
| Survivorship | |||||
| Required revision surgery or conversion to THA | 55 (19) | 34 (18) | 14 (21) | 7 (30) | .29 |
NOTE. R1 = undergoing first revision; R2 = undergoing second revision; R3+ = undergoing third or more revision.
THA, total hip arthroplasty.
Data are represented as mean ± standard deviation or number of patients (% of total).
Table 3.
Comparison of Patient Characteristics Between Patients Requiring Subsequent Surgery Versus Not∗
| No Subsequent Surgery n = 229 | Subsequent Surgery n = 55 | P Value | |
|---|---|---|---|
| Demographic and preoperative data | |||
| Revision group | .29 | ||
| R1 | 160 (70) | 34 (62) | |
| R2 | 53 (23) | 14 (25) | |
| R3+ | 16 (7) | 7 (13) | |
| Age, yr | 33 ± 11 | 31 ± 11 | .56 |
| Sex | .21 | ||
| Male | 95 (41) | 28 (51) | |
| Female | 134 (59) | 27 (49) | |
| Tönnis grade | .08 | ||
| 0 | 89 (40) | 17 (32) | |
| 1 | 115 (51) | 26 (49) | |
| 2 | 19 (9) | 10 (19) | |
| Minimum joint space, mm | 3.29 ± 0.74 | 3.07 ± 0.66 | .06 |
| Alpha angle, ° | 62 ± 17 | 58 ± 17 | .08 |
| Lateral center-edge angle, ° | 31 ± 6 | 29 ± 8 | .01 |
| Sharp’s angle, ° | 39 ± 2 | 39 ± 7 | .82 |
| Years from previous surgery to revision | 2.9 ± 2.5 | 3.1 ± 2.8 | .68 |
| Primary hip arthroscopy performed by senior author | 69 (30) | 21 (38) | .25 |
| Primary labral treatment | .12 | ||
| No treatment | 13 (6) | 5 (9) | |
| Debridement | 75 (33) | 10 (18) | |
| Repair | 138 (60) | 40 (73) | |
| Reconstruction | 3 (1) | 0 (0) | |
| Baseline outcome scores mHHS | 60 ± 16 | 58 ± 14 | .72 |
| HOS-ADL | 64 ± 17 | 62 ± 18 | .37 |
| HOS-Sport | 40 ± 25 | 34 ± 22 | .07 |
| WOMAC | 31 ± 16 | 34 ± 15 | .19 |
| SF-12 PCS | 39 ± 9 | 37 ± 8 | .13 |
| SF-12 MCS | 51 ± 11 | 51 ± 11 | .80 |
NOTE. R1 = undergoing first revision; R2 = undergoing second revision; R3+ = undergoing third or more revision.
HOS-ADL, Hip Outcome Score Activities of Daily Living; HOL-Sport, Hip Outcome Score Sport Score; mHHS, modified Harris Hip Score; SF-12 MCS, 12-Item Short Form Mental Component Score; SF-12 PCS, 12-Item Short Form Physical Component Score; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.
Data are represented as mean ± standard deviation or number of patients (% of total).
Table 4.
Comparison of Intraoperative Findings and Procedures Between Patients Requiring Subsequent Surgery Versus Not∗
| No Subsequent Surgery n = 229 | Subsequent Surgery n = 55 | P Value | |
|---|---|---|---|
| Intraoperative findings | |||
| Labrum | |||
| Tear | 116 (41) | 92 (40) | .64 |
| Deficient | 39 (14) | 30 (13) | .53 |
| Chondral lesions (Outerbridge grade 3/4) | |||
| Femoral head | 50 (22) | 17 (31) | .16 |
| Acetabulum | 44 (19) | 18 (33) | .03 |
| Residual femoroacetabular impingement (FAI) | |||
| Cam | 146 (64) | 38 (69) | .08 |
| Pincer | 136 (60) | 31 (56) | .68 |
| Adhesions | 209 (91) | 50 (91) | .78 |
| Ligamentum teres | |||
| Hypertrophy | 44 (19) | 12 (22) | .66 |
| Synovitis | 172 (75) | 42 (76) | .85 |
| Tear | 138 (60) | 33 (60) | .97 |
| Procedures performed during revision surgery | |||
| Labral treatment | |||
| Debridement | 55 (24) | 18 (33) | .18 |
| Repair | 69 (30) | 21 (38) | .25 |
| Augmentation | 20 (9) | 7 (13) | .37 |
| Reconstruction | 90 (39) | 22 (40) | .92 |
| Microfracture | |||
| Femoral head | 25 (21) | 3 (6) | .22 |
| Acetabulum | 19 (8) | 7 (13) | .31 |
| Capsular spacer | 45 (20) | 14 (25) | .34 |
| Capsular reconstruction | 40 (17) | 15 (27) | .10 |
| Lysis of adhesions | 209 (91) | 50 (91) | .78 |
| Ligamentum teres treatment | .48 | ||
| Debridement | 190 (83) | 47 (85) | |
| Primary repair | 2 (1) | 1 (2) | |
| Reconstruction | 2 (1) | 1 (2) |
Data are represented as mean ± standard deviation or number of patients (% of total).
There was no significant difference in failure incidence rate between revision groups (P = .29), but the hazard ratio (HR) for re-revision or THA was significantly greater for hips in the R3+ group compared with hips in the R1 group (HR 2.4, 95% CI 1.04-5.38, P = .04). Age, sex, or presence of Outerbridge grade 3/4 cartilage defects were not predictors of failure. When using the Cox model to adjust for age, sex and presence of Outerbridge grade 3/4 cartilage defects, there remained a significant increased risk of re-revision or THA for the R3+ group compared with the R1 group (HR 2.7, 95% CI 1.16-6.37, P = .02).
Discussion
The most important findings of this study were that the female sex, lower baseline PROs, smaller alpha angles, and a greater prevalence of capsular deficiency requiring capsule reconstruction were associated with more prior revision surgeries. In addition patients who underwent subsequent revision surgery or converted to THA had lower non-dysplastic LCEA and a greater prevalence of severe acetabular cartilage defects. Lastly, patients who underwent more than 3 previous revision surgeries had a significantly increased risk of failure compared with patients who underwent only one revision surgery when controlling for age, sex, and the presence of severe cartilage defects.
The present study identified female sex as a risk factor in patients who underwent an increased number of revision hip arthroscopy procedures. These findings are consistent with a systematic review by McCormack et al.28 in 2022 that assessed 48 hip arthroscopy studies, with 14 identifying female sex as a negative predictor regarding postoperative outcomes. More specifically, they identified 2 studies suggesting females >45 years at the time of surgery experienced significantly worse outcomes compared with their male counterparts.29,30 Although these findings may be of concern, McCormack et al.28 noted 58% of their included studies did not identify a statistical difference in postoperative outcomes between sexes, which was further validated in 2023 by Crofts et al.31 Despite the variability in the literature, the present study’s findings suggest female sex may be associated with an increased number of revision surgeries. Hip preservationists can use this information to more aggressively mitigate other modifiable factors associated with the need for a revision procedure such as adhesion formation, residual impingement, and their resulting pathologies.
The most common pathologies encountered in patients who underwent multiple revised hip arthroscopy procedures included residual impingement, labral pathology, and capsular deficiency. Better appreciation for these commonly encountered pathologies may lead to better mitigation strategies for prevention of reoperation at the time of primary hip arthroscopy with the goals being to relieve impingement, preserve the labrum, achieve capsular closure, and implement strategies to prevent adhesion formation. Despite the decreased survivorship reported in the present study among patients who underwent a third (or more) revision, the re-revision surgery and arthroplasty-free survival remains greater than 50% at mean follow-up of 4.3 years in this population. Although this may be acceptable to those pursuing the limits of hip preservation, further mitigation strategies are warranted to prevent a patient from undergoing multiple revision surgeries earlier in their treatment course.
It has been reported previously that patients who underwent multiple revision hip arthroscopy procedures often had worse PROs when directly compared with patients undergoing primary hip arthroscopy.5 The goal of investigating the multiply revised hip arthroscopy patient population was to identify risk factors that can potentially be mitigated early in a patient’s treatment course to improve patient satisfaction and survivorship. A secondary goal was to determine whether acceptable outcomes can still be achieved by performance of hip arthroscopy or whether these patients are better suited for THA. Although the present study utilized a retrospective cohort of patients, this single surgeon cohort was well suited for this purpose as some of the well-known risk factors for failed hip arthroscopy—including dysplasia, osteoarthritis, and increasing age—are minimally represented in the present series. The patients included had an average age of 33 years old with an average minimal radiographic joint space of >3 mm, and LCEA of 31°. By including a cohort with optimal age, joint space, and LCEA we were able to identify three common pathologies often encountered at the time of revision hip arthroscopy. These included adhesions, residual impingement, and factors contributing to disruption of the fluid seal and microinstability such as labral deficiency, labral tearing and/or capsular deficiency. Each one of these pathologies has separate underlying causes and mitigation strategies.
In one of the first series that reported on revision hip arthroscopic surgery, Philippon et al.32 detailed the most common abnormality encountered at the time of revision was residual FAI in 95% of cases. This result was later identified as the primary pathology encountered in the pediatric population at the time of revision hip arthroscopy as well.33 The current study reveals residual cam and pincer deformities were present in 76% and 60% of cases, respectively; however, as the number of revisions increase these rates drop to 52% and 50%, respectively. It is possible that increased awareness, improved preoperative imaging, including 3-dimensional computed tomography, and intraoperative resection guidance at the time of revision arthroscopy could have contributed to a lower rate of residual impingement at each consecutive revision. Although these rates are still high, it is possible that specialized hip fellowship training and intraoperative guidance can reduce the rates of residual impingement at the time of primary hip arthroscopy even further.
Although less commonly cited and more challenging to detect on clinical examination, early studies on revision arthroscopy revealed persistent instability at the time of revision to be present in approximately 35% of patients.32 Since the early publications, the definition of microinstability and its various causes have been better defined: labral insufficiency or deformity disrupting the suction seal, dysplasia, capsular insufficiency, ligamentum teres rupture, cam over-resection, generalized ligamentous laxity or a combination of the above factors.34,35 In the current study, labral or capsular insufficiency encountered at the time of revision surgery was addressed with labral augmentation or reconstruction 49% of the time, while capsular reconstructions were performed 19% in this multiple revision cohort. Surprisingly, more capsular reconstructions were performed at each subsequent revision arthroscopy: 13%, 28%, and 43% after the first through third revisions, respectively (P < .001). This finding likely represents both an increased understanding of the importance of capsular integrity and repair both in diagnosis and treatment over the course of time. In the beginning of the current study’s cohort, 2011, the senior author still routinely performed capsular closure but the capsular reconstruction technique and how to manage deficient capsule was still in its infancy. It is possible that more capsular reconstructions were performed with subsequent revisions because this technique was more readily available.36 Interestingly, in the current study rates of labral reconstruction and capsular reconstruction both increase with each subsequent revision which may indicate that microinstability may be more of an issue with each subsequent revision. Despite requiring further investigation, this may indicate that clinicians should have a high index for capsule and/or labral insufficiency in the multiply revised hip and be prepared for augmentation and reconstruction procedures in order to appropriately address these deficiencies.
Finally, adhesions were the most common pathology encountered in 92% of patients at the time of revision in the current study. It is yet unclear the significance of adhesions and they may be an expected outcome in the setting of acetabuloplasty and femoroplasty from bleeding bony surfaces. Some theorize that capsulolabral adhesions can lead to pathologic labral eversion with resultant loss of the fluid seal and microinstability.22,37 Because of the frequency of encountering adhesions at the setting of revision arthroscopy, several strategies, both mechanical and pharmacologic, have been employed in order to mitigate their formation. Postoperative hip circumduction exercises were introduced by Willimon et al.38 and were found to be protective for prevention of adhesion formation in a large retrospective study. Other strategies include postoperative CPM machines, early upright bicycling or aquajogging, all with the goal of early and frequent hip joint motion in order to prevent consolidation of blood clots to adhesions between structures.37 Furthermore, other mechanical strategies have been employed at the time of revision hip arthroscopy including placement of a capsulolabral allograft spacer when labral tissue is sufficient that can act not only as a sealant of the bleeding bony acetabular rim bed but also as a “chock block” to prevent pathologic labral eversion.22 Ruzbarsky et al.22 report on the results of this technique in conjunction with a lysis of adhesions in the revision setting with 65% of patients meeting the minimal clinically important difference threshold and a survivorship of 91% at minimum 2-year follow-up. Besides these mechanical techniques employed, pharmacologic prophylaxis is another intriguing option that has been investigated. Most attention has focused on the transforming growth factor beta pathway. The antihypertension drug, losartan, works as an angiotensin II–type receptor blocker which ultimately limits activation of transforming growth factor beta 1 and has been shown in other investigations to prevent fibrosis of other organs as well as improving skeletal muscle regeneration after injury.37 Unfortunately, although losartan has an excellent safety profile, animal models and human trials on its prevention of postoperative adhesions in the setting of hip arthroscopy are limited and its current use is considered off-label.
Despite the strategies aimed at mitigating the aforementioned pathologies encountered at the time of the multiply revised hip, the most important strategy for improving outcomes in hip arthroscopy is primary prevention at the time of the index hip arthroscopy. The approach of meticulous osteoplasties with dynamic exam and/or fluoroscopic examination with or without guidance, labral preservation and repair, capsular closure, and early postoperative motion should be employed by all hip arthroscopists to prevent failed primary surgeries. But in the multiply revised hip, if preoperative imaging or previous arthroscopic surgical images reveal high grade acetabular cartilage loss or evidence of borderline dysplasia (LCEA 20°-25°), patients should be counseled on a higher failure risk and consideration should be given to the patient for total hip arthroplasty as an alternative.
Limitations
This study has several limitations. First, given the rare nature of patients undergoing a multiply revised hip arthroscopy, the numbers are relatively small which limits the ability to draw significant conclusions. Second, given that this is a single surgeon series at a quaternary national- and international-based referral center, the findings and risk factors of this population may not be generalizable to smaller centers where patients under consideration for revision hip arthroscopy may be older, have worse radiographic joint space, and have evidence of dysplasia. In addition, we must acknowledge the inherent bias in deciding to perform a revision procedure following an index procedure performed by a different surgeon. Finally, this is a cross-sectional study examining the demographics and determining risk factors, but does not at all report on PROs after the revision surgeries.
Conclusions
At a minimum 2-year follow up, more previous revisions were associated with female sex, lower baseline PROs, capsular deficiency, and greater failure risk. Patients with lower nondysplastic LCEA, severe acetabular cartilage damage, or ≥3 revisions had elevated risk for re-revision or THA.
Disclosures
The authors report the following potential conflicts of interest or sources of funding: J.R. reports consulting fees from Smith & Nephew. J.E. reports consulting fees from Johnson & Johnson and Depuy Mitek Sports Medicine. M.J.P. reports grants from Smith & Nephew, Ossur, Arthrex, and Siemens; royalties or licenses from Bledsoe, ConMed Linvatec, DJO, Arthrex, Arthrosurface, SLACK, Elsevier, and Smith & Nephew; consulting fees from Smith & Nephew, MIS, Olatec, NICE Recovery Systems; Faculty/Speaker Compensation from Synthes GmbH; hospitality payments from Siemens; Board Member of Vail Health Services and ISHA (International Society of Hip Arthroscopy); General Council Member of Vail Valley Surgery Center , Steadman Philippon Surgery Center, and Dillon Surgery Center; Co-Chairman of the Steadman Philippon Research Institute; Advisory Board Member of Orthopedics Today; and Editorial Board of American Journal of Sports Medicine; stock or stock options from Arthrex, Arthrosurface, MJP Innovations, LLC, Vail MSO Holdings LLC, MIS, Vail Valley Surgery Center, EffRx, Olatec, iBalance (Arthrex), Stryker, 3M, Bristol Myers Squibb, Pfizer, AbbVie, Johnson & Johnson, Manna Tree Partners, Trimble, Grocery Outlet, and DocBuddy. All other authors (S.M.C., V.M.S., N.A.F., G.J.D.) declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Full ICMJE author disclosure forms are available for this article online, as supplementary material.
Footnotes
Research performed at The Steadman Philippon Research Institute Vail, Colorado, U.S.A.
Supplementary Data
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